What kinds of securities can I buy online?
You can buy almost any type of stock, bond, or mutual fund online.
What's the difference between a market order and limit order? Is one better than the other?
With a market order the customer instructs his or her brokerage firm to buy or sell a stock at whatever the price is when the trade is executed, presumably as soon as possible. If the price of the stock is moving quickly and there is a delay in the transmission of the order, then the price at which the customer purchases or sells the stock may be very different than what the customer expected when the order was placed. With a limit order, the customer specifies the price at which he or she is willing to buy or sell. Limit orders can help protect customers from rapid price changes when markets are moving fast. However, there is the risk that the limit order will not be executed. Also note that limit orders usually cost a bit more than market orders.